Oral care products by which various oral care substances or actives can be delivered to the soft and hard tissues of the oral cavity have previously been known. Examples of such oral care products include, for example, brushing aids such as dentifrice products for delivery of anti-caries actives such as fluoride or other actives for the reduction of the bacteria that lead to the formation of plaque, and mouthwashes containing breath freshening actives and/or anti-bacterial actives. In addition, bleaching agents such as peroxide that can be applied directly to the surfaces of the teeth, i.e., to the tooth enamel, have been developed.
However, it has been found that such conventional product forms typically do not provide substantivity sufficient to maintain actives on the hard and soft oral tissues for a period of time sufficient to enhance or prolong the therapeutic, prophylactic, and/or cosmetic benefits provided by the actives. Neither have such conventional product forms been able to provide sustained delivery of oral care actives, without periodic reapplication at relatively short time intervals, or without a special delivery device or containment means such as a mouthpiece.
One such system is disclosed in International Publication No. WO 98/55709  WO 98/55079, “A Delivery System for an Oral Care Substance Using a Strip of Material Having a Low Flexural Stiffness,“ published on Dec. 10, 1998. This system involves the combination of an oral care substance that directly contacts the oral cavity surfaces, and a flexible strip of material that is worn over the oral care substance, to protect the substance from erosion and from contact with other oral surfaces and, or saliva. In this system, the strip is worn in order to hold the composition in place for a sufficient amount of time to allow the active to act upon the oral surface.
Other attempts have previously been made to enhance the substantivity of whitening bleaches, bactericides, and other active components of oral care products. See, e.g., U.S. Pat. No. 5,425,953 to Sintov el al. on Jun. 20, 1995, in which a film forming, water-soluble cellulosic polymer is used to deliver a bleaching agent to the teeth; U.S. Pat. No. 5,438,076 to Friedman et al., in which liquid methacrylate acid copolymer compositions are used to deliver a bacteriocidal pharmacological agent; and International Patent Appln. No. PCT/CN97/00 to Huang, published on Jul. 24, 1997, disclosing a film-coating composition comprising cellulose and polyvinyl acetal, coumarone-indene resin, or shellac as a film former to deliver bleaches to the tooth enamel.
However, the above systems are water-soluble, i.e., they are readily dissolved by saliva, generally within about 1-3 hours after application. Therefore, their degree of durability is low, and they cannot provide long-term delivery of the active ingredient that is present in the composition. In addition, their water-soluble nature precludes them from being used with oral care actives that would be unstable in water-based films. Sodium percarbonate is one example of such an active; it would be unstable in the high pH environment of an aqueous-based film.
In order to provide an applied composition with a relatively higher degree of durability, the use of protective coatings that are applied to the teeth has been described. See, U.S. Pat. No. 5,401,528, to Schmidt on Mar. 18, 1995, in which organically modified silicic acid polycondensates are deposited on the teeth, then polymerized in-situ by curing, to coat the teeth in order to protect them from plaque deposits. This system is not a true delivery system by which an active ingredient is released over time; instead, it provides a barrier by which the deleterious effect of plaque-causing bacteria may be diminished.
Although such a barrier coating may offer a benefit in terms of enhanced durability, it requires the use of special equipment and complex application; thus, it cannot be performed at home and cannot be used for self-treatment.
Therefore, it can be seen that none of these previous developments can offer the combination of both long-term delivery of an oral care substance or active ingredient and the convenience of easy application, discreet self-treatment, and home use. Based on the foregoing, there is a need for a convenient delivery system for various oral care substances which is easy to apply and in which the substantivity of the active ingredients is enhanced. None of the existing art provides all of the advantages and benefits of the present invention.